1. Field of the Invention
This invention relates to adsorbents used in cigartte filters, air filters, protective masks, refrigerators and the like to remove harmful substances and disagreeable odor contained in cigarette smoke and air through adsorption.
2. Description of the Prior Arts
Conventional adsorbents used for such purposes are activated carbon, alumina, silica gel, zeolite and others. However, the substances to be adsorbed are very diverse in type. For example, cigarette smoke contains, other than nicotine, tar and carbon monoxide, 3,4-benzopyrene and other carcinogenic compounds; automotive and plant emissions contain various types of nitrogen oxides and sulfur oxides; and the air in refrigerators smells of various foodstuffs, often emitting unpleasant odor. When a variety of harmful or malodorous substances as mentioned above are present in air, it is difficult for any of the conventional adsorbents (activated carbon, etc.) to adsorb all of these at the same time. Adsorption activity of these adsorbents are also not sufficient.
Attempts have been made to use, in combination with the above-mentioned adsorbents, other substances that can effectively adsorb specific harmful or malodorous compounds, thus achieving adsorbent compositions with excellent adsorptive capacity.
Powder of algae, such as Chlorella and Spirulina, is one of substances used for this purpose, which is receiving attention for their unique adsorption activity against 3,4-benzopyrene and other harmful or malodorous compounds (U.S. Pat. No. 4,269,204 and Japanese Patent Laid-open No. 156584/1980).
The size of powder of these algae is very small; about 2 to 10.mu. in diameter for Chlorella, and 8.mu..times.400.mu. for Spirulina. If the powder is used as such, effective contact with the harmful or malodorous compounds cannot be expected. The result is insufficient exhibition of their excellent adsorption activity.
When this minute powder is used as adsorbent in cigarette filters, in particular, the suction force exerted during smoking forces them to pass through the fibrous filter base, thus affecting cigarette taste.
The same is true also when the alga powder is employed in combination with commonly used adsorbents, such as activated carbon, alumina, silica gel and zeolite; segregation occurs between these two types of adsorbent components differing in size and specific gravity, nullifying the effect of incorporation of alga powder.